106. In the previous chapters we have several
times referred to some limitations in the IPCC process. This process
is an international one involving all governments and hundreds
if not thousands of experts. Inevitably, in such a large-scale
venture there will be weaknesses and errors. But the stakes are
high and it is imperative that the process is an open one, capable
of receiving criticism, and insistent on the highest standards
of scientific and economic procedures. While HM Government and
the many UK experts comprise just one collective player in the
IPCC process, it is important that they are vigilant in ensuring
that any errors and defects are brought to the attention of the
IPCC and the scientific community in general. In this chapter
we elaborate on our previous concerns and introduce some others.

108. In terms of process, we heard from several
witnesses that the IPCC SRES exercise does not reflect the most
appropriate expertise. While there are some national accounts
statisticians involved in the exercise, it seems to us that a
broader representation from the economics and statistics community
is called for, along with a perspective from economic historians.
The failure to take adequate account of the consistency between
projections and past experience is a case in point, and an issue
that was raised early on by Professor Henderson and Mr Castles,
and again by Professor Tol and by Professor Ross McKitrick in
their evidence to us[89].

111. We can see no justification for this
procedure. Indeed, it strikes us as opening the way for climate
science and economics to be determined, at least in part, by political
requirements rather than by the evidence. Sound science cannot
emerge from an unsound process.

112. We sought examples of the kind of problem
that has arisen because of such interference in what should be
a scientific process. Examples were not hard to find. In the 1995
Second Assessment Report, the Summary of Chapter 6 on The Social
Costs of Climate Change bears little resemblance to the technical
chapter it is supposed to summarise. Indeed, the lead authors
of that chapter disowned the Summary. In the 2001 Working Group
II Report our attention was drawn to the following statement in
the Summary for Policymakers (p.8):

"Benefits and costs of climate change effects
have been estimated in monetary terms and aggregated to national,
regional and global scales. These estimates generally exclude
the effects of changes in climate variability and extremes, do
not account for the effects of different rates of change, and
only partially account for impacts on goods and services that
are not traded in markets. These omissions are likely to result
in underestimates of economic losses and overestimates of economic
gains [from climate change]"(our emphasis).

"Overall, the current generation of aggregate
estimates may understate the true cost of climate change because
they tend to ignore extreme weather events, underestimate the
compounding effect of multiple stresses, and ignore the costs
of transition and learning. However, studies also may have
overlooked positive impacts of climate change.Our current
understanding of (future) adaptive capacity, particularly in developing
countries, is too limited, and the treatment of adaptation in
current studies is too varied, to allow a firm conclusion about
the direction of the estimation bias" (our emphasis).

114. In short, the Summary says that economic
studies underestimate damage, whereas the chapter says the direction
of the bias is not known.

115. Given the global scale of the IPCC process,
it should be expected that it will attract the best experts. In
his evidence to us, Professor Paul Reiter raised doubts about
the extent to which this is the case[91].
He refers to the Second Assessment Report of Working Group II
in 1995, Chapter 18 of which is concerned with human health impacts
of warming. A significant part of this chapter discussed malaria.
Yet, according to Professor Reiter, none of the lead authors had
ever written a paper on malaria, the chapter contained serious
errors of fact, and at least one of the chapter's authors continues
to make claims about warming and malaria that cannot be substantiated.
Professor Reiter's concerns extend to the same chapter in the
Third Assessment Report of 2001, where he was initially a contributory
author. While he expresses far more confidence in this chapter
than the equivalent one in the Second Assessment Report, Professor
Reiter notes that "the dominant message was that climate
change will result in a marked increase in vector-borne disease,
and that this may already be happening". In Professor Reiter's
view, no such conclusion is warranted by the evidence, and he
speaks as a malaria specialist of more than thirty years' experience.
While nominated by the US Government to serve on the comparable
group for the Fourth Assessment Report, the next one that will
appear from IPCC, Professor Reiter learned that his nomination
had not been accepted by IPCC. Yet Professor Reiter tells us that
of the two lead authors for that chapter, one had no publications
at all and the other only five articles.

116. We cannot prove that Professor Reiter's
nomination was rejected because of the likelihood that he would
argue warming and malaria are not correlated in the manner the
IPCC Reports suggest. But the suspicion must be there, and it
is a suspicion that lingers precisely because the IPCC's procedures
are not as open as they should be. It seems to us that there remains
a risk that IPCC has become a "knowledge monopoly" in
some respects, unwilling to listen to those who do not pursue
the consensus line. We think Professor Reiter's remarks on "consensus"
deserve repeating:

"Consensus is the stuff of politics, not science.
Science proceeds by observation, hypothesis and experiment. Professional
scientists rarely draw firm conclusions from a single article,
but consider its contribution in the context of other publications
and their own experience, knowledge and speculations".

We are concerned that there may be political interference
in the nomination of scientists whose credentials should rest
solely with their scientific qualifications for the tasks involved.

117. In his evidence to us, Professor Ross McKitrick
suggested that the IPCC no longer commanded the allegiance of
mainstream economists[92].
In scrutinising the authorship of chapters, we believe his perception
has arisen because some of the economics that was originally subsumed
in Working Group III was moved in the 2001 Report to Working Group
II. Working Group II is concerned with impacts, adaptation and
vulnerability. Its authorship is dominated by impact specialists
who tend not to be economists. The fact that the chapter that
deals with monetised benefits of warming control now appears in
that volume may explain its apparent downgrading, although we
note that this is also consistent with IPCC's desire to avoid
the politically-inspired debates over the benefit estimates. Working
Group III deals with the remaining economic issues and the amount
of economic expertise is more significant.